Vladimir, 'java -X' usually prints out help on options, which start with -X.
What you was asking about as I understood that has syntax of -XX:<vm_option>[=<value>]. Sun's VM has help on these options on the Web page and no means to print it out to console. So, I'm -1 here for printing help on -XX options. If community still decide to print such help - there is 4-th way to do so (which will require changing.launcher). 1) launcher recognizes several generic options and is able to determine application class or jar name. 2) if no -vmdir or -vmdll is specified on command line - launcher tries to load that VM, otherwise defaults to <launcher location>/default/harmonyvm and tryies to load this one. If it fails - it prints short help message as it does right now, when launched with some unrecognizable property name. 3) if library is loaded successfully - launcher constructs arguments array (as it does right now) and calls to JNI_CreateJavaVM from loaded VM library. 4) if this call returns (-?, -h, -help and -X do not return from JNI_CreateJavaVM) and if launcher finds class of jar name on the command line - it proceeds with program startup. What do you think on such generic startup sequence? WBR, Pavel. On 6/20/07, Vladimir Beliaev <[EMAIL PROTECTED]> wrote:
Hello, All I want to add a *help *for drlvm specific system properties like '- Xvm.assert_dialog=false' (as asked in HARMONY-3409<http://issues.apache.org/jira/browse/HARMONY-3409> ). *Could you send your opinion on what way this can be done?* There are three safe ways to do this & non of them seems to be really good (please see technical details in HARMONY-3409<http://issues.apache.org/jira/browse/HARMONY-3409>). *way 1*: support 'java -Xhelp:prop foo' command line... Like if one runs 'java -X' then this help says "run '-Xhelp:prop foo' to see sytem properties"... In short: if one does not specify this 'foo' at the end, then a generic launcher consider command line as broken (no 'mainClass' is specified) & does not invoke JNI_CreateJavaVM (which print a help)... *way 2*: support 'java -Xhelp:prop' command line (i.e. w/o dummy 'foo')... To implement this the *generic* launcher is to be changed to recognize '-Xhelp:' as a 'help' option (like it recognizes ? -h -help -X now). Because of other VMs do not support such a '-Xhelp:' option we get *generic*launcher to be a bit drlvm-specific... *way 3*: be like other VMs and do not print a 'help for drlvm internal properties'. Instead, 'java -X' help output may provide a URL to harmony.apache.org html document explaining drlvm internal system properties... I would pick a *way 1* as it does not change *generic *launcher & we are free to do every thing we want with -X... I do not like *way 3* at all - it is not a big deal to create such a document, still it is one more document to be supported (I believe it may become out-of-date pretty in couple months)... So, what do you think? -- Thanks Vladimir Beliaev Intel Middleware Products Division
-- Pavel Pervov, Intel Enterprise Solutions Software Division
